In careful handwriting neatly penciled across a crisp page of wide-ruled paper, Tanya said she was sorry, sorry for all the people who got hurt.

After the Boston Marathon bombings, her class had gone around their Hyde Park school, collecting money for the One Fund for victims. They wanted to do something nice, the grade-schooler wrote, for “such wonderful people.”

“We felt so bad, wishing everything that happened didn’t happen,” Tanya wrote for her class. “God is watching over us now.”

As donations poured into the One Fund this spring, letters like Tanya’s came too, tender expressions of grief and sympathy for the bombing victims, of thanks for those who rushed to their side. They came by the thousands, sweet messages in folded construction paper, filled with earnest words of comfort and the hope to set things right.

“Dear one fund,” wrote Irenie and Sydney, from Roslindale. “Her is sum muny. We did a lemonade stand to get people better. We have $40 and 80 cents.”

Siblings Maeve and Finbar also hosted a lemonade stand, raising $75. In their letter, they explained how they stayed by the stand for hours, running to the curb everytime they saw a car roll by. They even ate lunch outside.

“We were very tired but happy to help,” they wrote, their words angling across the unlined page. “We are terribly sorry for the tragc events that took place at the Marathon.”

The siblings signed the letter “sincerely from our hearts.”

The One Fund has saved the correspondence and hopes to create a digital archive of the letters so they can be viewed online, and reach those wounded in the bombings.

Mike Sheehan, who serves on the One Fund board of directors, says the website could serve as a “digital museum” for the letters, preserving them for posterity.

“There should be a record of the generosity, of the goodness of people,” he said.

In all, the fund has received more than 50,000 letters, officials say.

On a recent visit to the One Fund’s office in the Prudential Center, a sampling of the letters underlined the deep sense of obligation behind the vast financial support, and how children were moved to action after the bombings, eager to help any way they could.

Kathryn, a sixth-grader from Brockton, gave all her birthday money to the One Fund, as did young Charlie from Topsfield, who asked the fund to “except these donations.”

Thirteen-year-old Eliza from Jamaica Plain donated the $200 she got from her bat mitzvah. An elementary school in Virginia Beach sent in $1,200, and a group of 9- and 10-year-olds in Weymouth donated $307.92, money raised by giving up their regular ice cream for two weeks.

In Standish, Maine, a group of third-grade girls pooled their allowances and sent in $263.

In their letters, many children described their efforts in endearing detail. Emily (favorite subject reading/art, dog named Winston) and Kristina (favorite subject science/art, cats named Sandy and Squeaky) decided to hold a bake sale featuring cupcakes, brownies, and gummy snacks. The 9-year-olds from Northborough raised $213.

On the card, they drew balloons that said “Keep on Running,” “1 Fund,” and “Always Finish.”

After the bombings, Meghan, an 8-year-old from Weymouth, began collecting coins from friends and family in a water bottle she decorated with hearts and smiley faces. When that filled up, she shifted to a giant cheeseball container. Two weeks later, she sent the One Fund $231.

“I raised the money to help you guys buy new legs, arms, pay your medical bills,” Meghan wrote with childlike bluntness. “Hope you feel better.”

Beyond letters, the One Fund received memorabilia from fund-raising efforts across the country, and banners and posters filled with messages of support. From Washington state to the Twin Cities to Dallas, cities covered cards with condolences, and in Connecticut, the people of Newtown sent their sympathies.

“Stick together,” one wrote. “There is strength in connectedness.”

Children struck the same theme. A girl named Cecilia, from Boston, drew a row of stick figures standing in front of the Boston skyline, holding hands.

“Stay strong and keep looking towards tomorrow,” she wrote in purple marker. “You have more positive thoughts and love coming your way than you can imagine.”

With a blue card dotted with red stars, Julia sent her thoughts to first responders, thanking them no fewer than six times.

“Thank you so much for responding to the Boston Bombing,” she wrote. “You went out of the blue and saved people’s lives without knowing if it was safe. That’s amazing!! You’re my hero!!”

Children’s letters contained many charming touches. Some, like Skyler in Boston, addressed his note to “Dear Boston,” and told their story the way only a kid could.

“Once I heard about the bombing I knew I had to do something,” he wrote. “I called some of my friends and asked if they heard about what happened. And they did.”

Ria, 9, sent a green condolence card to the victims. Like many kids her age, her spelling wasn’t perfect. But the message was true.

“I pray to everyone in boston,” she wrote. “And especially the ones that are ingerd and have past away.”

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